Thermodynamic Calculations of Phase Equilibria and Phase Fractions of a β-Solidifying TiAl Alloy using the CALPHAD Approach

摘要: The CALPHAD (CALculation of PHAse Diagrams) method is widely recognized as a powerful tool in both scientific and industrial development new materials processes. For the implementation consistent databases, where each phase described separately, models are used which based on physical principles parameters assessed from experimental data. Such database makes it possible to perform realistic calculations thermodynamic properties multi-component systems. However, commercial available TiAl can be applied for conventional Ti-base alloys complex intermetallic describe experimentally evaluated fractions function temperature. In present study were done β-solidifying alloy with nominal composition Ti-43.5Al-4Nb-1Mo-0.1B (in at. %), termed TNMTM alloy. At room temperature this consists ordered γ-TiAl, α2-Ti3Al β0-TiAl phases. certain α2 β0 disorder α β, respectively. Using reflect only qualitative trends more exact quantitative had improved high Nb (and Mo) contents, recently reported Nb-rich γ-TiAl alloys. Therefore, was modified by obtained microstructure analysis light-optical scanning electron micrographs well X-ray diffraction after long-term heat treatments means in-situ highenergy experiments. Based CALPHAD-conform assessment, optimized now correctly predict equilibria alloying system, interest applications automotive aircraft engine industry.